Electrolytic apparatus.



No. 742,443 PATENTED OCT. 27', 190s. W. MOA.y JOHNSON. ELEoTRoL-YTIGAPPARATUS.

APPLIOATION FILED JAN. 13', `1903.

THE MORRIS PETERS C0 PNYo-LHHO, WASHINGTON. D. c.

W/z'nesses: va@

uatented October 27, 1903.

UNITED STATES PATENT OFFICE.

WOOLSEY MCA. JOHNSON, OF HARTFORD, CONNECTICUT.

ELECTROLYTIC APPARATUS.

SPECIFICATION forming part of Letters Patent No. 742,443, dated October27, 1903'. Application filed January 13, 193. Serial No. 138,858. (Nomodel To @ZZ whom it may concern:

Be it known that I, WOOLSEY MOA. J OHN- SON, a citizen of the UnitedStates, residing at Hartford, in the county of Hartford and State ofConnecticut, have invented certain new and useful Improvements inElectrolytic Apparatus, of which the following isa speciflcation.

This invention relates to the electrodeposition of metals under suchconditions as will yield av deposit of improved character, and comprisesan apparatus particularly adapted to the electrodeposition of metals andto the treatment of the electrolyte.

In the deposition by means of electric current of such metals as areelectropositive to hydrogen, of which metals nickel may be taken as anexample, a certain quantity of hydrogen,dependingupon the currentdensity used, is liberated at the cathode at the same time that themetal is deposited thereon. This hydrogen is in part occluded bythedeposit, in part adheres thereto, and is in part dissolved by theelectrolyte or otherwise held therein. I have discovered that this gasin some or all of the conditions above stated exerts an injurious effectupon the tenacity, density, and other characteristics of theelectrodeposited metal. Furthermore, in the electrodeposition of metals,such as copper, which are electronegative to hydrogen an evolution ofgas may also occur at the cathode, especially when a certain limit ofcurrent density is exceeded. Such metals also are injuriously affectedby the gas. Furthermore, all liquids which are capable of serving aselectrolytes contain under normal conditions considerable quantities ofdissolved or otherwise retained gases, which may appear in part in theform of bubbles when the electrolyte is subjected to a slight rise oftemperature. These gases also I have found to aect the deposited metalin an injurious manner.

My apparatus is particularly adapted for depositing metals under suchconditions and with such materials as Will avoid the deleterious actionof such gases.

I have found that if the electrolyte is substantially freed from gasesbefore the metal is deposited therefrom, and especially if it bemaintained substantially free from gases during the plating operation,the quality of the separated metal is greatly improved, as evidenced byits increased density, hardness, and toughness, by its smooth surface,its freedom from Amicroscopic cavities, and by other physical andchemical characteristics. As a suitable and convenient means formaintaining the electrolyte in this gas-free condition I make use of avacuum or of such diminished pressure of air as will to a'suflicientextent accomplish the desired result. Under diminished atmosphericpressure the gases held or liberated within theelectrolyte quicklyescape therefrom, and the solution is therefore maintained in asubstantially gas-free condition. I prefer also to maintain theelectrolyte in circulation between fthe electrodes, and I may cause itto circulate through a suitable filter capable 'of removing andretaining any solid particles. I find that the diminished air-pressureabove referred to constitutes a .convenient means for accomplishing thiscirculation,and to this end I may exhaust the air from an elevatedreceivingtank, which preferably contains a vfilter and which is suitablyconnected with the electrolytic cell. vPortions of the electrolyte are'thereby transferred from the electrolytic tank to the filtering vesseland may then be permitted to flow again to the electrolytic tank. Byproviding a plurality of iiltering-tanks and using them alternately theflow of the electrolyte may be made continuous.

For a clear understanding of the invention reference is made to theaccompanying drawing, which shows one form of my apparatus in verticalsection, and Wherein- 1 indicates an electrolytic tank, and 2 3 anodesand cathodes mounted therein and suitably connected to a source ofelectric current.

4 is a closed overfioW-tank connected by a valved pipe 5 with theelectrolytic tank and by a valved pipe 6 with the filtering-tank 7. Saidtank '7 contains a distributing-plate 8 for the electrolyte, upon whichis preferably placed a suitable filter lO. Said tank 7 communicatesthrough a valved pipe 9 with a reservoir 11, from which the electrolyteis discharged through a pipe 12 to the electrolytic cell 1. Said pipe l2is preferably arranged, as shown, to draw the electrolyte from beneaththe surface, and said tank 11 is pref- IOO erably closed in order thatthe air above the surface of the electrolyte maybe maintained atdiminished pressure. Preferably pipes 5 and 12 are provided Within theelectrolytic tank, with perforated sections 5 and 12 extendingtransversely of the electrodes and serving to provide a distributed flowof the electrolyte along their surfaces.

The filtering-tank 7 is hermetically closed and communicates through avalved pipe 13 with a vacuum-pump or other device for relnoving gases.(Not shown.) Atrap 14 for collecting any liquid drawn over through pipe13 may be interposed, as shown, in the vacuumline. Said pipe 13 entersthe tank 7 below the filtering-layer 10, but above the normal level ofthe electrolyte.

In operation the electrolyte is permitted to flow from tank 7 throughpipe 9 into tank 11, thence through pipes 12 and 12', the electrolyticvat 1, and pipes 5 and 5 to the tank 4. By the operation of the pump theliquid in tank 4 is raised through pipe 6, discharging above the filterin tank 7. The liquid then flows through the filter and the severaltanks, as before specified. In this construction the flow of theelectrolyte is necessarily intermittent; but it will be readilylinderstood that by providing a plurality of tanks 7 with suitableconnections thereto and by using such tanks in alternation the flow maybe rendered continuous. It will thus be seen that portions of theelectrolyte are submitted to the action of diminished air-pressure,serving, as above stated, to withdraw therefrom the contained gases. Theelectrolyte reaches the electrolytic tank 1 in a virtually gas freecondition, and the fiow through such tank should be sufficient totransfer the electrolyte to the filtering-tank 7 with sufficientrapidity to maintain the gas content low enough to avoid injury to thedeposit.

The electrolytic tank l may be open to the atmosphere. In certain cases,however, it is desirable that such tank should be closed and shouldcommunicate with the air-pump in order that gases liberated by theelectrolysis may be rapidly withdrawn and the electrolyte maintained atall times in a substantially gas-free condition.

It is obvious that the overflow-tank 4 may be open to the atmospherewithout interfering in any manner with the operation of my device andthat the apparatus may be otherwise modified without departing from thespirit of my invention. I prefer, however, that the several tanks beclosed and placed in communication with the vacuum-pump, inasmuch asadditional liquid-surface for the liberation of gases is therebyprovided.

I claiml. An electrolytic apparatus comprising a tank, electrodestherein, and means for supplying electrolyte to such tank in asubstantially gas-free condition, as set forth.

2. An electrolytic apparatus comprising a tank, electrodes therein,means for supplying electrolyte to such tank in a substantially gas-freecondition, and means for rapidly withdrawing gases from the electrolyteduring the depositing operation, as set forth.

3. An electrolytic apparatus comprising an electrolytic tank, electrodestherein, a closed supply-tank therefor, and means for exhausting gasesfrom said supply-tank, as set forth.

4. An electrolyzing apparatus comprising a closed electrolytic tank,electrodes therein, a closed supply-tank therefor, and means forexhausting gases from said electrolytic tank and supply-tank, as setforth.

5. An electrolytic apparatus comprising an electrolytic tank, electrodestherein, a closed supply-tank therefor, means for exhausting gases fromsaid supply-tank, and connections between said electrolytic tank andsupplytank, whereby a circulation of the electrolyte may be maintained,as set forth.

6. An electrolytic apparatus comprising an electrolytic tank, electrodestherein, a closed supply-tank therefor above the level of saidelectrolytic tank, means for exhausting gases from said supply-tank,connections between said electrolytic tank and supplytank, whereby acirculation of the electrolyte may be maintained, and a filtering deviceinterposed in said connections, as set forth.

7. In an electrolytic apparatus an electrolytic tank, electrodestherein, a supply-tank therefor, an exhaust-line from said supplytank,and a distributing-plate in said supplytank, as set forth.

IOO

8. In an electrolytic apparatus an electrolytic tank, electrodestherein, a supply-tank therefor, an exhaust-'line from said supplytank,and a filter in the said supply-tank, as set forth.

9. In an electrolytic apparatus an electrolytic tank, electrodestherein, an elevated supply-tank, a filter in said supply-tank,connections between said electrolytic tank and supply-tank, and meansfor exhausting gases from one or more of said tanks, as set forth.

10. An electrolytic apparatus comprising a tank, a soluble anode and asuitable cathode therein, and means for supplying electrolyte to suchtank in a substantially gas-free condition, as set forth.

1l. An electrolytic apparatus comprising a tank, a soluble anode and asuitable cathode therein, means for supplying electrolyte to such tankin a substantially gas-free condition, and means for rapidly withdrawinggases from the electrolyte during the depositing operation, as setforth.

In testimony whereof I affix my signature in presence of two witnesses.

WOOLSEY MCA. JOHNSON.

Witnesses:

S. S. THORNTON, H. C. MCCORMACK.

l'IO

